Descartes arrived on 4 October 1649, and tutored her for the next 4 months until he caught pneumonia and died ten days later on 11 February 1650. Speculations have been made as to the causes of his illness. Some cite the icy weather, others argue it could have been elicited by the rigorous schedule asked of Descartes by the queen. In 1991 a German scholar published a book questioning this account and more arguments against its veracity have been raised.[1][2]